Hi folks

I hope I am doing this properly if not please let me know. I have been out of the game for a long time so some of this look like dumb questions. Last week I bought a 1989 iroc vert with 137,000 orig kms it is all stock except for what looks to be Trans Am wheels and a 6 speed manual gear box the guy I bought it off was 87 and has Alzhimers he bought it 1990 from a friend of his who is a GM dealer and said he alonf with GM had modified it for use as a pace car at the local speedway so I am not sure what trans this is and I want to pull out the 305 TPI out and with as little fuss as possible drop in something with 400-500 hp I have a line on a 2004 LS6 out of a Z06 vet that has been converted to a carb set up I was reading the swap guide for this and it requires alot of crossmember changes if I am reading correctly is there an engine that I should be looking for as a starting point that would be a better fit. I know I have not likely provided enough info so ask away LOL Sorry the last time I played around in the hot rodder game was 25 years ago when every thing was easy no FI and every small block fit LOL must be a mid life crissis

 

its most likely got the t56 6speed swapped in from a 4th gen fbody. if thats the case, then its an LT car t56 which wont work with the ls6 you want to get. youd have to change out the input shaft to the longer ls t56 input shaft. if you want to go efi then youll need to step up and get an aftermarket efi system, the tpi cant support decent hp in the higher rpms. itll just limit what ever built motor you put in. if you want to go carb then it makes thing easier. you can swap any gen 1 sbc in the place of the 305 with minimal effort. the 6 speed will even bolt right up with no issues. going LSx requires a lot more work and $. you need specialty parts like LS swap headers, and those things arent cheap.

 

Thanks for the quick response is there a way for me to verify which trans it is as the owner said the swap was done in 89 but I don't believe GM had a 6 speen in 89

 

post some pics of the trans and well be able to tell you pretty quick if its a t56 or not. and im sure someone will be able to identify it if it isnt.

 

Cool I will snap a few pics as soon as it stops raining

 

trans.zipThis is a good as can get for now

 

cant really tell much from the pics.

 

however in 89 chevy introduced the zf 6 speed in the c4 corvette. so it possible thats what you have.

 

I'll try to get it in the air tomorrow thanks for the help

 

the label for dextron 2 makes me think its the zf6 not the t56. t56 uses dextron 3

 

So if it a zf which blocks will it bolt up to and can you tell me why I have the dual cat exhaust with a 305 and no le1

 

if its a zf 6, its pretty much the same thing as the LT t56. its only a direct bolt on for gen 1 sbc.

 

the 1LE only refers to the brakes. nothing else. anyone who tells you otherwise is mis informed and is perpetuating a myth. you can have 1LE without dual cats, and you can have dual cats without 1LE

 

Looks like a LT1 t56 to me..

 

yea, but that dextron II sticker is what makes me think it really was installed in 89. which would make it most likely the ZF6.

both transmissions look similar, as you can see in the pics. the first is a ZF6, the second is a t56. it looks like the easiest way to tell is the position of reverse on the shift gate. t56 is all the way to the right and up, zf6 is all the way to the right and down.